A preheating mechanism and a low-temperature vacuum crystallization evaporator comprising the same

Abstract

The present application relates to the technical fields of low-temperature evaporator, in particular to a preheating mechanism and a low-temperature vacuum crystallization evaporator containing the mechanism, which comprises a mounting frame, further comprises an evaporator, the bottom of the outer side of the evaporator is provided with a heat exchange element, and the outside of the compressor is provided with a heat dissipation element; a crystallization concentrating assembly, which comprises a lifting block slidingly arranged in the evaporator, and a plurality of collecting plates are arranged on the outer ring wall of the lifting block; an intermittent discharging assembly, which comprises a filter frame installed in the evaporator, a blocking frame is vertically slidingly arranged below the filter frame, a flow guide ring is slidingly installed on the inner wall of the evaporator, and a flow guide hole is formed in the flow guide ring, and the blocking frame and the flow guide ring are synchronously lifted. The working temperature of the compressor itself is reduced, waste heat is recovered, the dependence of the system on external heat source is effectively reduced, and the overall energy utilization rate is significantly improved; the crystallization is automatically concentrated and cleaned, wall adhesion is avoided, intermittent automatic discharging is realized, and continuous operation is realized.

Description

Technical Field

[0001] This invention relates to the field of low-temperature evaporator technology, and more specifically to a preheating mechanism and a low-temperature vacuum crystallization evaporator containing the mechanism. Background Technology

[0002] A low-temperature vacuum crystallization evaporator is a device that achieves low-temperature evaporation and crystallization by lowering the boiling point of a solution in a vacuum environment. It is widely used in chemical, pharmaceutical, food processing, wastewater treatment, and seawater desalination industries. Its working principle is as follows: a vacuum pump or vacuum generator evacuates the evaporator to a vacuum state (typically around -96 kPa), significantly lowering the boiling point of the solution (e.g., to around 33°C). The solution is then heated by a heating system, causing the water to evaporate at a low temperature. The solute in the solution precipitates crystals due to supersaturation.

[0003] In existing low-temperature vacuum crystallizing evaporators, the compressor is the core power component of the heating system. The compressor acts on the refrigerant, controlling the pressure of the refrigerant at different heat exchange points to achieve heat output, providing the necessary heat source for the evaporation and crystallization process. However, in addition to providing heating heat to the evaporator, the compressor itself generates a significant amount of compression heat during operation. This heat is usually discharged directly into the environment during refrigerant circulation or heat dissipation, failing to be effectively utilized. Simultaneously, during the evaporation and crystallization process, water in the solution continuously evaporates, the solute concentration continuously increases, and a large amount of crystals precipitate. Some of these crystals remain suspended in the liquid, while others gradually deposit and firmly adhere to the inner wall of the evaporator. Crystal adhesion to the wall not only reduces the heat transfer efficiency of the evaporator and increases energy consumption but also reduces the effective volume of the equipment, and in severe cases, even clogs pipes, forcing frequent shutdowns for manual cleaning. Furthermore, existing equipment lacks effective collection methods for crystals free in the solution, making it difficult to remove and recover them. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a preheating mechanism and a low-temperature vacuum crystallizing evaporator containing the mechanism, which can effectively solve the problems of low heat utilization and difficulty in cleaning internal crystals in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a preheating mechanism, including a mounting bracket, and further comprising: An evaporator is mounted on a mounting bracket, and a compressor is also mounted on the mounting bracket. A heat exchange component is provided on the bottom outer side of the evaporator, and a heat dissipation component is provided on the outside of the compressor. The heat dissipation component transfers the heat from the compressor to the heat exchange component. A crystallization concentrator for assisting crystallization deposition includes a lifting block slidably disposed in an evaporator. The outer ring wall of the lifting block is provided with multiple collecting plates. The lifting block is connected to a scraping ring. When the lifting block moves upward, the collecting plates move downward and flip over. When the lifting block moves downward, the multiple collecting plates close and block the inner ring of the scraping ring. An intermittent discharge assembly for discharging deposited crystals includes a filter frame installed inside an evaporator, a blocking frame vertically slidably disposed below the filter frame, a guide ring slidably disposed on the inner wall of the evaporator, and a guide hole opened on the guide ring. The blocking frame and the guide ring move up and down synchronously. When the lifting block moves down to the filter frame, the blocking frame moves up to block the filter hole of the filter frame.

[0006] Furthermore, the heat exchanger includes a heat exchange tube wound around the bottom of the outer wall of the evaporator, and a circulation pump is connected to the outside of the heat exchange tube. The middle section of the heat exchange tube is also wound around the outside of the compression molding machine.

[0007] Furthermore, the crystallization concentrator includes a reciprocating lead screw rotatably mounted in the evaporator, and the lifting block has a threaded hole adapted to the reciprocating lead screw. A support rod is fixedly installed in the evaporator, and the support rod moves through the lifting block.

[0008] Furthermore, multiple fixing rods are fixedly installed on the outer wall of the lifting block, and the ends of the multiple fixing rods away from the lifting block are connected to a sliding ring. The scraping ring is installed on the top wall of the sliding ring, and the inner wall of the scraping ring is provided with a guide surface.

[0009] Furthermore, a slide frame is slidably mounted on the outer wall of the lifting block, and the collecting plate is rotatably mounted on the slide frame.

[0010] Furthermore, a slider is fixedly installed on the outer wall of the lifting block, a slide groove adapted to the slider is provided on the slide frame, a rotating rod is provided on the slide frame, and an insertion hole adapted to the rotating rod is provided on the collecting plate.

[0011] Furthermore, a scraper is fixedly installed on the bottom wall of each of the collection plates, and the scraper is set at an angle.

[0012] Furthermore, the intermittent discharge assembly also includes a liquid outlet hole opened on the inner wall of the evaporator. When the guide ring moves upward, the guide hole gradually aligns with the liquid outlet hole. A crystallization collection ring is provided on the outside of the evaporator, and the liquid outlet hole is connected to the crystallization collection ring. A filter screen is provided in the crystallization collection ring, and a return pipe is connected between the crystallization collection ring and the evaporator. The connection position of the return pipe and the evaporator is lower than the bottom of the sealing frame.

[0013] Furthermore, the sealing frame is provided with a sealing plate that is compatible with the filter frame, and a movable rod is fixedly installed at the center of the sealing frame. The movable rod moves through the center of the filter frame and is movably inserted into the bottom end of the reciprocating screw.

[0014] Furthermore, a transmission ring is fixedly installed on the movable rod, a rotating plate is rotatably installed on the sealing frame, a first connecting plate is fixedly installed at the top of the rotating plate, a second connecting plate is fixedly installed at the bottom of the rotating plate, and the top of the second connecting plate is in full contact with the bottom of the transmission ring. A pressure rod is movably connected to the top wall of the first connecting plate, and the top of the pressure rod movably penetrates the bottom wall of the filter frame. A pressure plate is fixedly installed at the top of the pressure rod.

[0015] Furthermore, the evaporator is provided with a condenser plate, and a condenser frame is movably sleeved on the reciprocating screw. The inner wall of the condenser frame is provided with multiple flow guides.

[0016] A low-temperature vacuum crystallization evaporator employs the aforementioned preheating mechanism.

[0017] The technical solution provided by this invention has the following advantages compared with the known prior art: By installing heat dissipation components outside the compressor and winding heat exchange tubes between the compressor and the bottom of the evaporator, the compression heat generated by the compressor operation is transported to the bottom of the evaporator for preheating using a circulating pump. This not only reduces the operating temperature of the compressor itself but also achieves waste heat recovery, effectively reducing the system's dependence on external heat sources and significantly improving the overall energy utilization rate.

[0018] The lifting block drives the scraping ring to slide up and down along the inner wall of the evaporator. When it moves up, the scraping ring scrapes off the crystals attached to the inner wall. At the same time, the collection plate moves down and flips, so that the scraped crystals fall down along the guide surface to the bottom of the collection plate. When it moves down, multiple collection plates close, pushing the crystals to the bottom of the evaporator. This effectively prevents the long-term adhesion of crystals from causing a decrease in heat transfer efficiency and a reduction in volume, and greatly reduces the frequency of manual cleaning.

[0019] When the lifting block moves down to the filter frame, the sealing frame moves up to block the filter frame holes through the pressure plate, pressure rod and linkage plate structure. At the same time, the guide ring moves up to align the guide hole with the liquid outlet hole. The concentrated liquid containing crystals is discharged to the crystal collection ring through the liquid outlet hole. After the filter screen traps the crystals, the clear liquid returns to the evaporator through the return pipe, realizing the automatic separation and collection of crystals, ensuring that the equipment can operate continuously and stably for a long time and improving production efficiency. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is an overall schematic diagram of the present invention; Figure 2 This is a schematic diagram of the evaporator section in this invention; Figure 3 This is a schematic diagram of the internal structure of the evaporator in this invention; Figure 4 This is a schematic diagram of the cleaning frame after it has been retracted in this invention; Figure 5 This is a schematic diagram of the structure of the cleaning frame after it has been unfolded in this invention; Figure 6 for Figure 5 Enlarged view of the structure of part A in the middle; Figure 7 This is a cross-sectional view of the filter frame portion in this invention; Figure 8 for Figure 7 Enlarged view of the structure of section B; Figure 9 for Figure 7 The front view; Figure 10 This is a cross-sectional view of the condenser rack portion in this invention; Figure 11 This is a flowchart of the evaporator's operation.

[0022] The labels in the diagram represent: 1. Mounting bracket; 2. Evaporator; 3. Collection tank; 4. Waste liquid pipe; 5. Drain pipe; 6. Sliding ring; 7. Scraper ring; 8. Fixed rod; 9. Collection plate; 10. Lifting block; 11. Motor; 12. Reciprocating screw; 13. Scraper; 14. Condensate tray; 15. Condensate rack; 16. Flow guide rack; 17. Support rod; 18. Filter rack; 19. Sealing rack; 20. Flow guide ring; 21. Flow guide hole; 22. Pressure plate; 23. Pressure rod; 24. Rotating plate; 25. First connecting plate; 26. Second connecting plate; 27. Movable rod; 28. Transmission ring; 29. ​​Slider; 30. Slide rack; 31. Condensate collection ring; 32. Crystallization collection ring; 33. Compressor. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] The present invention will be further described below with reference to embodiments.

[0025] Example 1:

[0026] A preheating mechanism includes a mounting frame 1 and an evaporator 2 mounted on the mounting frame 1. A compressor 33 is also mounted on the mounting frame 1. A heat exchange component is provided at the bottom outer side of the evaporator 2, and a heat dissipation component is provided on the outside of the compressor 33. The heat from the compressor 33 is transferred to the heat exchange component through the heat dissipation component. The heat exchange component includes a heat exchange tube wound around the bottom outer wall of the evaporator 2, and a circulation pump is connected to the outside of the heat exchange tube. The middle section of the heat exchange tube is also wound around the outside of the compression molding machine.

[0027] The evaporator 2 is equipped with a condenser plate 14, and a condenser rack 15 is movably sleeved on the reciprocating screw 12. Multiple flow guides 16 are provided on the inner wall of the condenser rack 15.

[0028] like Figure 1 , Figure 2 As shown, a heat exchange tube is wound around the bottom outer side of the evaporator 2. This heat exchange tube, acting as a heat exchange element, is tightly fitted to the bottom outer wall of the evaporator 2 to transfer heat to the bottom of the evaporator 2. Similarly, a middle section of a heat exchange tube is wound around the outside of the compressor 33. This section acts as a heat dissipation element to absorb the compression heat generated during the operation of the compressor 33. A circulation pump is also connected externally to the heat exchange tubes, driving the heat transfer medium (such as heat transfer oil or water) inside the heat exchange tubes to circulate continuously.

[0029] The specific working process is as follows: When compressor 33 starts running, the refrigerant inside it compresses, generating a large amount of heat, and the body temperature rises rapidly. The heat exchange tubes surrounding compressor 33 absorb the heat from the body, raising the temperature of the medium inside the tubes. The circulating pump continues to work, transporting the high-temperature medium along the heat exchange tubes to the tubes surrounding the bottom outer wall of evaporator 2. As the high-temperature medium flows through the bottom of evaporator 2, heat is transferred through the tube walls and the wall surface of evaporator 2 to the solution inside evaporator 2, raising the solution temperature and accelerating water evaporation. After releasing heat, the medium's temperature decreases, and it flows back to the outside of compressor 33 via the circulating pump to absorb heat again, forming a complete thermal cycle.

[0030] This process effectively reduces the operating temperature of compressor 33, preventing it from overheating, and recovers the compression heat that would otherwise be directly discharged into the environment for solution preheating, reducing reliance on external heat sources such as electric heating or steam heating, and significantly reducing the overall energy consumption of the equipment.

[0031] At the same time, such as Figure 3 As shown, the low-temperature steam generated by evaporation rises to the condenser plate 14 and condenser rack 15, and after exchanging heat with the cooling medium, it condenses into liquid water, which is collected along the guide rack 16 and discharged from the evaporator 2, realizing the synchronous and continuous operation of evaporation and condensation. A condensation collection ring 31 is also set outside the evaporator 2, and a collection tank 3 is connected to the outside of the condensation collection ring 31. The two are connected by a drain pipe 5.

[0032] The bottom of the evaporator 2 is also connected to a waste liquid pipe 4, which discharges the concentrated waste liquid.

[0033] Example 2:

[0034] This embodiment mainly involves the specific structure of the crystallization concentration component and the crystallization scraping and concentration process.

[0035] like Figure 4 , Figure 5 , Figure 6 As shown, the crystallization concentrator includes a lifting block 10 vertically slidingly disposed inside the evaporator 2. A reciprocating screw 12 is rotatably mounted in the evaporator 2. The lifting block 10 has a threaded hole adapted to the reciprocating screw 12. A support rod 17 is fixedly mounted in the evaporator 2, and the support rod 17 movably passes through the lifting block 10, guiding the lifting block 10 and preventing it from rotating with the reciprocating screw 12. A motor 11 is fixedly mounted outside the evaporator 2, and its output end is connected to the reciprocating screw 12 for transmission, driving the reciprocating screw 12 to rotate forward and backward.

[0036] Multiple fixing rods 8 are fixedly installed on the outer wall of the lifting block 10. The ends of the multiple fixing rods 8 away from the lifting block 10 are connected to a sliding ring 6. The outer wall of the sliding ring 6 slides in contact with the inner wall of the evaporator 2. A scraping ring 7 is fixedly installed on the top wall of the sliding ring 6. The inner wall of the scraping ring 7 has a guide surface to guide the scraped crystals to slide down.

[0037] A slider 29 is fixedly installed on the outer wall of the lifting block 10. A sliding groove adapted to the slider 29 is provided on the slide frame 30, allowing the slide frame 30 to slide up and down along the outer wall of the lifting block 10. A collecting plate 9 is rotatably mounted on the rotating rod of the slide frame 30 through its insertion hole. An inclined scraper 13 is fixedly installed on the bottom wall of each collecting plate 9. Multiple collecting plates 9 are evenly distributed around the outer ring wall of the lifting block 10.

[0038] The specific work process is as follows: The motor 11 drives the reciprocating lead screw 12 to rotate, and the reciprocating sliding of the lifting block 10 is completed through the thread transmission action of the reciprocating lead screw 12 and the threaded hole on the lifting block 10.

[0039] The lifting block 10 moves upwards: Under the action of the screw thread, the lifting block 10 moves upwards along the reciprocating screw 12. The lifting block 10 drives the sliding ring 6 and the scraping ring 7 to move upwards synchronously through the fixed rod 8. The outer wall of the scraping ring 7 slides tightly against the inner wall of the evaporator 2, scraping off the crystal layer attached to the inner wall of the evaporator 2. The scraped crystals slide down the guide surface of the inner wall of the scraping ring 7 to below the scraping ring 7. At the same time, when the lifting block 10 moves upwards, it is impacted by the downward solution. Meanwhile, the slide 30 slides downwards along the slider 29 under its own gravity and the gravity of the collecting plate 9 (i.e., moves downwards relative to the lifting block 10). Under the action of solution resistance, the collecting plate 9 flips and unfolds downwards around the rotating rod, forming multiple inclined collecting surfaces. The crystals that slide off the scraping ring 7 and the crystals suspended in the solution are deposited above the collecting surface of the collecting plate 9 under the action of gravity.

[0040] The lifting block 10 moves downwards as follows: The lifting block 10 moves downwards along the reciprocating screw 12. As the lifting block 10 moves downwards, the slide 30 slides upwards along the slider 29 under the influence of buoyancy and resistance from the solution (i.e., moves upwards relative to the lifting block 10). Simultaneously, the collecting plates 9 flip upwards and close under the resistance of the solution, gradually closing to form a nearly closed annular surface, blocking the inner annular channel of the scraping ring 7. As the lifting block 10 continues to move downwards, the multiple closed collecting plates 9 are pushed downwards as a whole, pushing the crystals and concentrated solution above the collecting plates 9 together towards the bottom of the evaporator 2.

[0041] Through the above-mentioned reciprocating motion of upward scraping and downward concentration, the crystals on the inner wall of evaporator 2 are cleaned regularly, and the suspended crystals are continuously concentrated to the bottom, effectively preventing the decrease in heat transfer efficiency and reduction in equipment volume caused by the adhesion of crystals to the wall surface.

[0042] Example 3:

[0043] This embodiment mainly involves the specific structure of the intermittent discharge component and the intermittent discharge process of crystallization.

[0044] like Figure 7 , Figure 8 , Figure 9 As shown, the intermittent discharge assembly includes a filter frame 18 fixedly installed inside the lower part of the evaporator 2. The filter frame 18 has multiple evenly distributed filter holes to allow solution to pass through while trapping crystals. A sealing frame 19 is vertically slidably installed below the filter frame 18, and the sealing frame 19 has sealing plates corresponding one-to-one with the filter holes of the filter frame 18. A flow guide ring 20 is slidably installed on the inner wall of the evaporator 2. The flow guide ring 20 has flow guide holes 21. The sealing frame 19 and the flow guide ring 20 are fixedly connected by a connecting rod to achieve synchronous lifting and lowering.

[0045] An outlet hole (not marked in the figure) is provided on the inner wall of the evaporator 2, and the position of the outlet hole corresponds to the guide hole 21 on the guide ring 20. A crystallization collection ring 32 is provided on the outside of the evaporator 2, and the outlet hole is connected to the crystallization collection ring 32 through a pipe. A filter screen is provided inside the crystallization collection ring 32 to trap crystalline solids. The bottom of the crystallization collection ring 32 is connected to the side wall of the evaporator 2 through a return pipe, and the connection position of the return pipe to the evaporator 2 is lower than the bottom of the sealing frame 19 to ensure that the liquid can return by gravity.

[0046] A movable rod 27 is fixedly installed at the center of the sealing frame 19. The upper end of the movable rod 27 movably passes through the center of the filter frame 18 and is movably inserted into the bottom end of the reciprocating screw 12, ensuring that the movement direction of the sealing frame 19 is related to that of the lifting block 10. A transmission ring 28 is fixedly installed on the movable rod 27. A rotating plate 24 is rotatably installed on the sealing frame 19. A first connecting plate 25 is fixedly installed at the top of the rotating plate 24, and a second connecting plate 26 is fixedly installed at the bottom of the rotating plate 24. The top of the second connecting plate 26 is in full contact with the bottom of the transmission ring 28. A pressure rod 23 is movably connected to the top wall of the first connecting plate 25. The top end of the pressure rod 23 movably passes through the bottom wall of the filter frame 18, and a pressure plate 22 is fixedly installed at the top end of the pressure rod 23. The pressure plate 22 is located above the filter frame 18.

[0047] The specific work process is as follows: As the lifting block 10 moves downward, multiple collecting plates 9 push the crystallized and concentrated solution to the area above the filter frame 18. When the lifting block 10 continues to move downward to near the filter frame 18, the bottom of the lifting block 10 first contacts and presses down on the pressure plate 22. The pressure plate 22 drives the pressure rod 23 to move downward, and the bottom end of the pressure rod 23 pushes down the first connecting plate 25, causing the rotating plate 24 to rotate around its hinge point. The second connecting plate 26 at the bottom end of the rotating plate 24 then tilts upward. When the second connecting plate 26 tilts upward, it pushes the transmission ring 28 and the movable rod 27 to move upward. The movable rod 27 drives the sealing frame 19 to move upward as a whole. After the sealing frame 19 moves upward, the sealing plate on it is inserted into the filter hole of the filter frame 18, sealing the filter hole and preventing the solution from continuing to seep downward during the discharge process.

[0048] Simultaneously, the sealing frame 19 drives the guide ring 20 to move upward synchronously via the connecting rod. During the upward movement of the guide ring 20, its guide holes 21 gradually align with the liquid outlet holes on the inner wall of the evaporator 2. At this time, the concentrated crystallized solution above the filter frame 18 flows out of the evaporator 2 through the liquid outlet holes and guide holes 21, entering the crystallization collection ring 32. The filter screen inside the crystallization collection ring 32 traps the crystal particles within the ring, while the clear liquid flows back into the evaporator 2 through the return pipe, maintaining liquid level balance and solution circulation.

[0049] When the lifting block 10 completes the discharge and moves upward away from the pressure plate 22, the pressure plate 22 and the pressure rod 23 lose their downward pressure and reset under gravity. The first linkage plate 25 resets accordingly, the rotating plate 24 rotates, the second connecting plate 26 moves downward, and the transmission ring 28 and the movable rod 27 move downward and reset under gravity and the weight of the sealing frame 19. As the sealing frame 19 moves downward, the sealing plate disengages from the filter holes of the filter frame 18, the filter holes reopen, and the solution resumes normal filtration flow. At the same time, the guide ring 20 moves downward, the guide hole 21 closes off from the liquid outlet, and the discharge ends.

[0050] Through the intermittent discharge action described above, this embodiment achieves automatic timed discharge of crystals and solid-liquid separation, eliminating the need for manual cleaning during machine shutdown and ensuring continuous operation of the equipment.

[0051] A low-temperature vacuum crystallization evaporator employs a preheating mechanism.

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preheating mechanism, comprising a mounting bracket, characterized in that, Also includes: An evaporator is mounted on a mounting bracket, and a compressor is also mounted on the mounting bracket. A heat exchange component is provided on the bottom outer side of the evaporator, and a heat dissipation component is provided on the outside of the compressor. The heat dissipation component transfers the heat from the compressor to the heat exchange component. A crystallization concentrator for assisting crystallization deposition includes a lifting block slidably disposed in an evaporator. The outer ring wall of the lifting block is provided with multiple collecting plates. The lifting block is connected to a scraping ring. When the lifting block moves upward, the collecting plates move downward and flip over. When the lifting block moves downward, the multiple collecting plates close and block the inner ring of the scraping ring. An intermittent discharge assembly for discharging deposited crystals includes a filter frame installed inside an evaporator, a blocking frame vertically slidably disposed below the filter frame, a guide ring slidably disposed on the inner wall of the evaporator, and a guide hole opened on the guide ring. The blocking frame and the guide ring move up and down synchronously. When the lifting block moves down to the filter frame, the blocking frame moves up to block the filter hole of the filter frame.

2. The preheating mechanism according to claim 1, characterized in that, The heat exchanger includes a heat exchange tube wound around the bottom of the outer wall of the evaporator, and a circulation pump is connected to the outside of the heat exchange tube. The middle section of the heat exchange tube is also wound around the outside of the compression molding machine.

3. A preheating mechanism according to claim 1, characterized in that, The crystallization assembly includes a reciprocating lead screw rotatably installed in the evaporator, and the lifting block has a threaded hole adapted to the reciprocating lead screw. A support rod is fixedly installed in the evaporator and moves through the lifting block.

4. A preheating mechanism according to claim 1, characterized in that, Multiple fixing rods are fixedly installed on the outer wall of the lifting block. The ends of the multiple fixing rods away from the lifting block are connected to a sliding ring. The scraping ring is installed on the top wall of the sliding ring, and the inner wall of the scraping ring is provided with a guide surface.

5. A preheating mechanism according to claim 1, characterized in that, A slide frame is slidably installed on the outer wall of the lifting block, and the collecting plate is rotatably installed on the slide frame.

6. A preheating mechanism according to claim 5, characterized in that, A slider is fixedly installed on the outer wall of the lifting block, a slide groove adapted to the slider is opened on the slide frame, a rotating rod is provided on the slide frame, and an insertion hole adapted to the rotating rod is provided on the collecting plate.

7. A preheating mechanism according to claim 1, characterized in that, A scraper is fixedly installed on the bottom wall of each of the collection plates, and the scraper is set at an angle.

8. A preheating mechanism according to claim 1, characterized in that, The intermittent discharge assembly also includes a liquid outlet hole on the inner wall of the evaporator. When the guide ring moves upward, the guide hole gradually aligns with the liquid outlet hole. The outside of the evaporator is provided with a crystallization collection ring, and the liquid outlet hole is connected to the crystallization collection ring. The crystallization collection ring is provided with a filter screen, and a return pipe is connected between the crystallization collection ring and the evaporator. The connection position of the return pipe and the evaporator is lower than the bottom of the sealing frame.

9. A preheating mechanism according to claim 3, characterized in that, The sealing frame is equipped with a sealing plate that is compatible with the filter frame. A movable rod is fixedly installed at the center of the sealing frame, and the movable rod moves through the center of the filter frame and is movably inserted into the bottom end of the reciprocating screw.

10. A preheating mechanism according to claim 1, characterized in that, A transmission ring is fixedly installed on the movable rod, a rotating plate is rotatably installed on the sealing frame, a first connecting plate is fixedly installed at the top of the rotating plate, a second connecting plate is fixedly installed at the bottom of the rotating plate, and the top of the second connecting plate is in full contact with the bottom of the transmission ring. A pressure rod is movably connected to the top wall of the first connecting plate, and the top of the pressure rod movably penetrates the bottom wall of the filter frame. A pressure plate is fixedly installed at the top of the pressure rod.

11. A preheating mechanism according to claim 3, characterized in that, The evaporator is equipped with a condenser plate, and a condenser frame is movably sleeved on the reciprocating screw. The inner wall of the condenser frame is equipped with multiple flow guides.

12. A low-temperature vacuum crystallization evaporator, employing a preheating mechanism as described in any one of claims 1-11.

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